THREATENS ICONIC TREE

Tuesday

A deadly palm tree disease, once confined to Manatee County, has spread and threatens to decimate the state's iconic sabal palms.

An insect with a disgusting habit is transmitting the disease, called Texas Phoenix Palm Decline. Experts are worried it will kill trees statewide.

The first documented case was in 2006 in Manatee County. Since then, it has been detected in Hillsborough, Pinellas and Polk counties, although experts say Manatee County is still the hardest-hit area.

If the condition spreads throughout the state's native sabal palms, it could change the entire Florida landscape, said Monica L. Elliott, a professor of plant pathology at the University of Florida's Fort Lauderdale Research and Education Center. The sabal palm is Florida's state tree and appears on the state flag and seal.

The disease is spread by a plant-hopper insect but the exact kind of bug is not yet known, according to University of Florida's Institute of Food and Agricultural Sciences. The insects pierce the palm leaves, then vomit -- and the vomit spreads the bacteria that causes the disease.

The bacteria wither the bottom palm leaves first. Those leaves turn yellow and eventually die, then the bacteria affect the young spear leaf and eventually the entire tree is killed.

"It's pretty scary," said Brian Dick, assistant superintendent for parks in the city of Lakeland. "We've invested quite heavily in our palm trees over the past 25 years. To have a disease come out of nowhere and kill our palm trees, it's pretty disappointing."

Dick estimates that 20 to 30 percent of the city's 700 Phoenix palms -- a type of tree that includes the expensive and showy Sylvester palm -- are infected with the disease. An unknown number of sabal palms within the city are also infected, he said.

Elliot said it is troubling that the state tree -- the native sabal palm -- is also affected by the disease.

While landscapers and cities can manage the condition with antibiotic injections, that is only likely to happen with expensive trees. It is less feasible to do so in wild sabal palms, she said.

"We would be losing a large population of a native palm that is found throughout the entire state. We wouldn't see it in the natural areas," she said.

Elliott and other UF researchers are trying to determine which planthopper insect is responsible for the Texas Phoenix Palm Decline. The insect and disease were first detected 30 years ago in Texas.

Texas Phoenix Palm Decline is similar to lethal yellowing, a disease which largely affects coconut palms in South Florida.

Palm decline has been spotted as far east as Lakeland and as far south as Sarasota. A few trees planted by landscapers in North Florida have also been found to be infected. But the disease is less likely to sweep into northern Florida; the insect and the bacteria cannot survive the cold.

Jane Morse, a commercial horticulture extension agent for Pinellas County, said the disease spreads rapidly and must be treated quickly with antibiotics.

"You don't want to leave any infected trees around. They act as a source of infection," she said.

Morse and other tree experts added that tree owners should not over-prune their palms because then the disease becomes harder to detect.

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